Java EE 8 Design Patterns and Best Practices

Implementing the EmployeeStoreManager class

The EmployeeStoreManager class is responsible for connecting with the data source as well as reading and writing employee data:

import com.packt.javaee8.entity.Employee;import java.util.HashMap;import java.util.Map;public class EmployeeStoreManager {    private Map<Object, Employee> dataSource = new HashMap<>();    public void storeNew ( Employee employee ) throws Exception {        if( dataSource.containsKey( employee.getId() ) ) throw new Exception( "Data already exist" );        dataSource.put( employee.getId(), employee );    }    public void update ( Employee employee ) throws Exception {        if( !dataSource.containsKey( employee.getId() ) ) throw new Exception( "Data not exist" );        dataSource.put( employee.getId(), employee ...